The present invention relates generally to torque transmitting couplings between a driving tractor and a trailing or driven farm or agricultural implement, and, more particularly, to a wide-angle joint used in such a torque transmitting coupling to allow for tilting or swiveling movement of the various connecting parts of the coupling as a result of riding over irregular terrain or turning the tractor and trailing implement about a curve or corner.
Wide-angle joints have been known for the transmission of driving torque from a farm tractor to a trailing or otherwise attached agricultural implement.
Some of the prior proposals for such wide-angle joints have been structured with external guide means, such as chain drives or meshing gear segment pairs as shown in FIGS. 4 and 5 (see Duditza, "Cardan Joint Transmissions and Their Applications", VDI-Verlag). While this type of external guide means permits wide-angle tilting or swiveling through an angle of more than 90.degree., the mechanism is capable of tilting or swiveling in only a single plane. Accordingly, distortion or bending forces on the joint occurring in other planes may result in fracture of one or more of the structural elements forming the joint.
Previously, it has been proposed that the tilting or swiveling plane in wide-angle joints of this type, be fixed in a horizontal plane, note FIGS. 4 and 5 showing such an arrangement. Fixing the tilting plane in the horizontal plane will allow the tractor with the trailing implement to be driven about curves and corners, since the coupling between the tractor and the trailing implement will tilt, swivel or otherwise pivot about a vertical axis. The fixing of the tilting plane in the horizontal plane, however, will not permit the coupling to compensate for movement about the longitudinal or transverse axes of the transmission which may occur in the coupling as a result of travel over irregular terrain.
Another type of wide-angle joint is disclosed in German PS No. 948,568. In this wide-angle joint, a pair of spherical housing members are concentrically engaged with each other to provide pivotal movement about a fixed common centerpoint. This type of arrangement has a maximum swivel angle of only 80.degree., and has the further disadvantage that the cooperating surfaces of the spherical members must be specially treated which tends to be relatively expensive. Additionally, this type of wide-angle joint requires external concentric alignment means having relatively large dimensions. Further, when tilting or swiveling movements occur, variations in the length of the wide-angle joint result, since the center of the swiveling action necessarily coincides with the common centerpoint of the spherical members. As a result, special provisions must be made to compensate for such length variations.
Accordingly, it is the primary object of the present invention to provide a wide-angle joint for use in torque transmission couplings having external guide means permitting tilting movement of the joint about a vertical axis of the coupling as a result of driving the tractor with the trailing implement about curves or corners, and also permitting movement about the longitudinal and transverse horizontal axes of the coupling as a result of driving the tractor and trailing implement over irregular terrain, and without causing torsional forces within the joint.